ActiveRecord-like query builder

qwry.js

var events = require('events');

var actions = [
  'find'
	, 'create'
	, 'update'
	, 'remove'
];

// These accept hashes to transform to key/val property pairs
var hashers = [
	'where'
];

// These do nothing with arguments
var noops = [
	'and'
	, 'not'
];

var sorters = [
	'sortBy'
	, 'sort_by'
];

var sorterDirections = [
	'ascending'
	, 'descending'
];

var other = [
	'include'
];

// All valid flaggers are grouped together
var flaggers = other
	.concat(sorters)
	.concat(sorterDirections)
	.concat(actions)
	.concat(noops)
	.concat(hashers);

function Qwry (table, options) {
	var relations = options.relations || [];
	var props = options.properties || [];

	var ev = new events.EventEmitter();
	var current;

	var state = {
		where: []
		, sort: []
	};

	// Not lets you turn negation on for the next property
	var not = false;
	ev.on('not', function () {
		not = true;
	});

	// Sort DESC by default
	ev.on('ascending', function () {
		var last = state.sort[state.sort.length - 1];
		last.order = 'ASC';
	});

	// End the currently running command and run it's behaviour
	function dispatcher () {
		var args = Array.prototype.slice.call(arguments);
		ev.emit.apply(ev, [current].concat(args));
		current = null;

		return dispatcher;
	}

	// Expose state externally
	// Probably better to add a serializer function instead
	dispatcher.state = state;
	dispatcher.emitter = ev;

	// The flagger flags that we are using a particular command
	// This lets us fake getters as actual callers
	function flagger (cmd) {
		dispatcher.__defineGetter__(cmd, function () {
			if (current) dispatcher();
			current = cmd;

			return dispatcher;
		});
	}

	// All tokens and properties are turned into legal flag functions
	flaggers.forEach(flagger);
	relations.forEach(flagger);
	props.forEach(flagger);

	// Hashes change mode and forward hash data to property receivers
	hashers.forEach(function (mode) {
		ev.on(mode, function (props) {
			state.mode = mode;
			if (typeof props === 'object') {
				Object.keys(props).forEach(function (prop) {
					ev.emit(prop, props[prop]);
				});
			}
		});
	});

	// Listen to sorts from both `sort` and `by`
	sorters.forEach(function (sorter) {
		ev.on(sorter, function (props) {
			state.mode = 'sort';

			if (typeof props === 'object') {
				Object.keys(props).forEach(function (prop) {
					ev.emit(prop, props[prop]);
				});
			}
		});
	});

	actions.forEach(function (action) {
		ev.on(action, function (cb) {
			state.action = action;
			ev.emit('execute', state, cb);
		});
	});

	// Push key/value pairs to the relevant mode list
	[['property', props], ['relation', relations]].forEach(function (group) {
		group[1].forEach(function (prop) {
			ev.on(prop, function (value) {
				if (state.mode === 'sort') {
					state.sort.push({
						type: group[0]
						, name: prop
						, direction: value || 'DESC'
					});
				} else {
					state[state.mode].push({
						type: group[0]
						, name: prop
						, value: value
						, not: !!not
					});

					// Remember to disable negation after
					not = false;
				}
			});
		});
	});

	return dispatcher;
}

// Create new query chain builder
var User = Qwry('user', {
	properties: ['username','email','banned']
	, relations: ['parent']
});

// Test all the parts
var q = User.where
	.username('me')
	.parent({ parent_id: 1 })
	.and.email('[email protected]')
	.and.not.banned(true)
	.sort_by.email('ASC')
	.sort_by({ username: 'DESC' });

// Fake the execution for now...
q.emitter.on('execute', function (state, cb) {
	console.log('state is', state);

	var user = {};
	state.where.forEach(function (c) {
		user[c.name] = c.value;
	});

	cb(user);
});

// Find user
q.find(function (user) {
	console.log(user);
});

result.json

{
   "where": [
      {
         "type": "property",
         "name": "username",
         "value": "me",
         "not": false
      },
      {
         "type": "relation",
         "name": "parent",
         "value": {
            "parent_id": 1
         },
         "not": false
      },
      {
         "type": "property",
         "name": "email",
         "value": "[email protected]",
         "not": false
      },
      {
         "type": "property",
         "name": "banned",
         "value": true,
         "not": true
      }
   ],
   "sort": [
      {
         "type": "property",
         "name": "email",
         "direction": "ASC"
      },
      {
         "type": "property",
         "name": "username",
         "direction": "DESC"
      }
   ],
   "mode": "sort",
   "action": "find"
}